1. Field of the Invention
This invention relates generally to child safety control systems, and more particularly to such a control system capable of discriminating between the movements of an adult and a small child or baby through a monitored portal.
2. Description of Related Art
The following art defines the present state of this field:
Feher, U.S. Pat. No. 4,910,498 describes an infrared light emitter forming a beam of infrared light directed onto a set of mirrors or reflecting surfaces arranged to form a closed path about a swimming pool and spaced above the pool deck a sufficient amount so as to be intercepted by anyone who might walk through it. After the reflected beam has traversed the closed path about the pool, it then impinges upon a light detector. An electric circuit provides a continuous alarm which can either be sound or visual upon beam interruption and which must be manually reset before it becomes inactive. The monitoring system may be actuated so the operative state by a hand-held radio frequency transmitter. Electrical poser for the system can be a rechargeable battery which is recharged by a solar array mounted directly onto a part of the system obviating the need for interconnecting cable wiring.
Sackett, U.S. Pat. No. 4,701,751 describes an alarm system for a swimming pool or the like whereby small inexperienced children or animals are detected prior to entering the pool or after an unauthorized entry into the water of the pool. The invention comprises the use of a height sensing apparatus employing fiber optics and a logic circuit whereby an interruption of the lowest light path only sounds an alarm. The invention further comprises the use of fiber optics and a movement sensor connected to the optics. Any impact on the water surface of he pool causes the sensor to change the state of the light transmission therethrough by transmitting or interrupting light transmission. This change of normal state activates the alarm. The invention still further comprises a wireless means for detecting a person in the pool water or a man overboard from a ship or the like and sounding an alarm.
U.S. Pat. No. 5,757,274 describes an apparatus for providing an automatic crib gate position indication of a crib having a gate that can be positioned in an open or a closed condition, said apparatus comprising a gate sensor means, having a transmitter, coupled to the crib that wirelessly transmits a first signal indicative of the open condition to a baby monitoring system, the baby monitoring system including a baby unit adjacent the crib and a parent unit remotely-located from the crib and whereby the baby unit wirelessly transmits a second signal indicative of the baby sounds that is received by said parent unit, said first signal being received by said parent unit and controlling a crib gate indication means therein.
Gustavsson, U.S. Pat. No. 5,625,340 describes a device for supervising an area in particular the crossing area between railway gates, in order to detect objects occurring in the area comprises a detector adapted to transmit detection signals and receive their reflection caused by objects. The detector is pivotably arranged in a reciprocal manner so as to transmit the detection signals in an angular area. The detector may be a laser, the light of which forms the detection signals.
Byrne, U.S. Pat. No. 5,554,972 describes an apparatus and method to provide an electronic perimeter warning system to prove the ingress or egress of persons or machines from a selected area such as in an area along the perimeter of a roof under construction. Battery powered signal transmitters and receivers establish a signal beam between two locations. When the continuity of the signal beam is broken, an alarm is sounded to warn the person who is crossing the signal beam of imminent danger.
Nakamura et al., U.S. Pat. No. 5,255,301 describes an apparatus for counting the number of passing persons by stature, wherein a projector is positioned for radiating light toward the head of a passing person, a light receiving lens for receiving light reflected from the person's head and alight position detector are arranged as one set at an upper portion of a gateway or a passageway. The light receiving lens converges reflected light to different light-received positions of the light position detector according to the height of the reflective position. The light position detector outputs electric signals which differ according to the reflected light received at the light-received positions and a counting operation performed discriminately for every output of the signals.
Britt, U.S. Pat. No. 5,844,487 describes an alert alarm responsive to the passage of child unaccompanied by an adult. An adult sensor is placed at an adult height higher than any anticipated child. A child sensor is placed at a height lower than the height of the shortest anticipated child. Actuator circuitry is actuated if a child passes the child sensor within a limited time either before or after the adult passes.
Jones, II et al., U.S. Pat. No. 5,831,527 describes a system to prevent cheating at a casino gaming table, where sensors are strategically positioned about a casino gaming table to monitor the movement about certain established area on the gaming table during certain established times during the play of the game. The tripping of a sensor in response to the detection of unauthorized movement about a certain area of the table sends a signal to a monitoring system which in turn alerts the casino so that the casino may respond to the unauthorized movement accordingly. The system of sensors can be used with a wide variety of card-based or chip-based casino gaming tables.
Thornton, U.S. Pat. No. 5,793,291 describes an alarm system for detection the presence of a person locked in a parked automobile. The alarm system includes a motion detector and a temperature detecting element coupled to a NOR gate. The motion detector transmits a low signal to the NOR gate once it detects motion within the interior of the automobile. The temperature detecting element transmits a low signal to the NOR gate if the temperature in the automobile exceeds a pre-determined extreme temperature. The NOR gate, upon receiving low signals from both the temperature detecting element and the motion detector, transmits an alarm signal.
Slomowitz et al., U.S. Pat. No. 5,757,274 describes a crib gate position indicator for use with a baby crib to automatically alert the parent or infant-caretaker, who is at a location outside of the room or location of the baby crib, when the crib gate has been left in an open condition. Other variations of this crib gate position indicator are used in conjunction with a baby monitoring system, thus supplementing a baby monitoring system with the ability to provide a crib gate position indication, in addition to permitting the parent or infant-caretaker to listen to the sounds being made by the baby.
The prior art teaches clearly teaches a number of distinct techniques for the detection of hazards related to small children and babies. However, the prior art does not teach that a movement alarm may be adapted to sensing the movement of a small child or baby in a manner similar to that of Britt, but with greater security and fail safe control. The present invention fulfills these needs and provides further related advantages as described in the following summary.